Exploiting Real-Time Genomic Surveillance Data to Assess 4cmenb Meningococcal Vaccine Performance in Scotland 2015-2022

Abstract

The UK implemented the first infant immunisation schedule for meningococcal vaccine 4CMenB (‘Bexsero®’) in September 2015, targeting serogroup B invasive meningococcal disease (IMD). Bexsero® contains four variable subcapsular proteins and post-implementation IMD surveillance was necessary as non-homologous protein variants can evade Bexsero®-elicited protection. We investigated post-implementation IMD cases reported in Scotland from the 1st September 2015 to 30th June 2022. Patient demographics and vaccination status were combined with genomic data from the causative meningococci, which was used to assess vaccine coverage with the Meningococcal Deduced Vaccine Reactivity (MenDeVAR) Index.

Eighty-two serogroup B IMD cases occurred in children <5 years of age, 48 (58.5%) were unvaccinated and 34 (41%) had received ≥1 Bexsero® dose.  15/34 vaccinated children received one dose, 17 received two doses and 2 received three doses. For 39 cases, meningococcal genome sequences enabled MenDeVAR Index deductions of vaccine-preventable (M-VP) and nonvaccine-preventable (M-NVP) meningococci. None of the 19 children immunised ≥2 times had IMD caused by M-VP meningococci, with 2 cases of NVP meningococci, and no deduction possible for 17. Amongst the 15 children partially vaccinated to schedule (1 dose), 7 were infected by M-VP meningococci and 2 with M-NVP meningococci, with 6 with no deductions possible. Of the IMD cases in unvaccinated children, 40/48 were ineligible for vaccination and 20/48 had IMD caused by M-VP meningococci, with deductions not possible for 14 meningococci.

These data are consistent with 2 and 3 doses of Bexsero® providing good protection against IMD caused by M-VP.  Single doses provide poorer protection to infants. These data can provide public health reassurance when vaccinated individuals develop IMD with non-vaccine preventable variants. Additional testing is needed on variants with insufficient immunological data, to improve protection estimates. We demonstrate the value of post-implementation genomic surveillance of vaccine preventable pathogens, providing information on real-world vaccine performance.

Note: This conference abstract was presented at the 17th Vaccine Conference organized by the journal Vaccine. This abstract has not been screened by SSRN for potential for public harm and should not be used to inform any clinical decision making. No competing interests or funding statements have been declared.